Systems and methods for producing propylene

ABSTRACT

According to one or more embodiments described herein, propylene may be produced by a process which may comprise one or more of at least partially metathesizing a first portion of a first stream to form a first metathesis-reaction product, at least partially cracking the first metathesis-reaction product to form a cracking-reaction product.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/191,009 filed Jun. 23, 2016 entitled “SYSTEMS AND METHODS FORPRODUCING PROPYLENE,” which claims the benefit of U.S. ProvisionalApplication Ser. No. 62/188,068 filed Jul. 2, 2015, where the entirecontents of each are incorporated by reference.

BACKGROUND Field

The present disclosure generally relates to processes and systems forproducing propylene, and more specifically, to processes and systems forproducing propylene from process streams comprising butene.

Technical Background

In recent years, there has been a dramatic increase in the demand forpropylene to feed the growing markets for polypropylene, propyleneoxide, and acrylic acid. Currently, most of the propylene producedworldwide is a byproduct from steam cracking units which primarilyproduce ethylene, or a by-product from FCC units which primarily producegasoline. These processes cannot respond adequately to a rapid increasein propylene demand.

Other propylene production processes contribute to the total propyleneproduction. Among these processes are propane dehydrogenation (PDH),metathesis reactions requiring both ethylene and butene, high severityFCC, olefins cracking, and methanol to olefins (MTO). However, propylenedemand has increased and propylene supply has not kept pace with thisincrease in demand.

Regarding the production of propylene by metathesis requiring ethyleneand butene, generally, a stoichiometric ratio of about 1 butene to 1ethylene is desirable for high product yield. However, in some cases,ethylene is not available, or is not available in great enoughquantities compared to butene supply. Therefore, such processesrequiring butene and ethylene may not be feasible due to lack ofethylene supply available for reaction. Accordingly, ongoing needs existfor a process for efficiently converting butene to propylene, andspecifically for efficiently converting butene to propylene without theneed for ethylene.

BRIEF SUMMARY

In accordance with one or more embodiments of the present disclosure,propylene may be produced by a process which may comprise one or more ofat least partially metathesizing a first portion of a first stream toform a first metathesis-reaction product, at least partially crackingthe first metathesis-reaction product to form a cracking-reactionproduct, combining a second stream with a second portion of the firststream to a form a mixed stream, the second stream comprising ethylene,and at least partially metathesizing the mixed stream to form a secondmetathesis-reaction product. The first stream may include butene.

In accordance with one or more additional embodiments of the presentdisclosure, propylene may be produced by a process comprising which maycomprise one or more of dividing a first stream into a first portion anda second portion, at least partially metathesizing a first portion of afirst stream to form a first metathesis-reaction product, at leastpartially cracking the first metathesis-reaction product to form acracking-reaction product, and at least partially metathesizing thesecond portion of the first stream to form a second metathesis-reactionproduct. The first stream may include butene.

In accordance with one or more additional embodiments of the presentdisclosure, propylene may be produced by a process comprising at leastpartially metathesizing a first portion of a first stream to form afirst metathesis-reaction product, least partially cracking the firstmetathesis-reaction product to form a cracking-reaction product, atleast partially separating ethylene from at least the cracking reactionproduct to form a first recycle stream, combining the first recyclestream with a second portion of the first stream to a form a mixedstream, and at least partially metathesizing the mixed stream to from asecond metathesis-reaction product. According to embodiments, the firststream may comprise butene, the cracking reaction product may comprisepropylene and ethylene, the first recycle stream may comprise ethylene,and the second metathesis-reaction product may comprise propylene.

In accordance with one or more additional embodiments of the presentdisclosure, propylene may be produced by a process comprisingintroducing a first portion of a first stream comprising butene to afirst reactor, at least partially metathesizing the first portion of thefirst stream with the first metathesis catalyst to form a firstmetathesis-reaction product, at least partially cracking the firstmetathesis-reaction product with a cracking catalyst to produce acracking-reaction product, passing the cracking-reaction product out ofthe first reactor in a cracking-reaction product stream, combining afirst recycle stream with a second portion of the first stream to a forma mixed stream and introducing the mixed stream to a second reactor, atleast partially metathesizing the mixed stream with a second metathesiscatalyst in the second reactor to produce a second metathesis-reactionproduct and passing the second metathesis-reaction product out of thesecond reactor in a second metathesis-reaction product stream. Theprocess may further comprise at least partially separating ethylene fromthe cracking-reaction product stream, the second metathesis-reactionproduct stream, or a stream comprising a mixture of both, to form thefirst recycle stream. Additionally, the process may comprise at leastpartially separating propylene from the cracking-reaction productstream, second metathesis-reaction product stream, or a streamcomprising a mixture of both, to form a product stream comprisingpropylene. According to embodiments, the first reactor may comprise afirst metathesis catalyst and a cracking catalyst, the cracking-reactionproduct may comprise propylene and ethylene, the first metathesiscatalyst may be positioned generally upstream of the cracking catalyst,the second reactor may comprise a second metathesis catalyst, and thesecond metathesis-reaction product may comprise propylene.

In accordance with one or more additional embodiments of the presentdisclosure, propylene may be produced by a process comprisingintroducing a first portion of a first stream comprising butene to afirst reactor, at least partially metathesizing the first portion of thefirst stream with a first metathesis catalyst to form a firstmetathesis-reaction product, introducing the first metathesis-reactionproduct to a second reactor, at least partially cracking the firstmetathesis-reaction product with a cracking catalyst to produce acracking-reaction product comprising propylene and ethylene, passing thecracking-reaction product out of the second reactor in acracking-reaction product stream, combining an ethylene recycle streamwith a second portion of the first stream comprising butene to a form amixed stream and introducing the mixed stream to a third reactor, atleast partially metathesizing the mixed stream with the secondmetathesis catalyst in the third reactor to produce a secondmetathesis-reaction product comprising propylene and passing the secondmetathesis-reaction product out of the third reactor in a secondmetathesis-reaction product stream. The process may further comprise atleast partially separating ethylene from the cracking-reaction productstream, the second metathesis-reaction product stream, or a streamcomprising a mixture of both, to form the ethylene recycle stream.Additionally, the process may further comprise at least partiallyseparating propylene from the cracking-reaction product stream, thesecond metathesis-reaction product stream, or a stream comprising amixture of both, to form a product stream comprising propylene.According to embodiments, the first reactor may comprise a firstmetathesis catalyst and a cracking catalyst, and the third reactor maycomprise a second metathesis catalyst.

In accordance with one or more additional embodiments of the presentdisclosure, systems may be operable to perform the processes forproducing propylene described in this disclosure.

Additional features and advantages of the technology described in thisdisclosure will be set forth in the detailed description which follows,and in part will be readily apparent to those skilled in the art fromthe description or recognized by practicing the technology as describedin this disclosure, including the detailed description which follows,the claims, as well as the appended drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The following detailed description of specific embodiments of thepresent disclosure can be best understood when read in conjunction withthe following drawings, where like structure is indicated with likereference numerals and in which:

FIG. 1 is a generalized diagram of a first butene conversion system,according to one or more embodiments described in this disclosure;

FIG. 2 is a generalized diagram of a second butene conversion system,according to one or more embodiments described in this disclosure;

FIG. 3 depicts a bar graph displaying the product distribution in wt. %(weight percent) of the system of FIG. 1, according to one or moreembodiments described in this disclosure; and

FIG. 4 depicts a bar graph displaying the product distribution (in wt.%) of the system of FIG. 2, according to one or more embodimentsdescribed in this disclosure.

For the purpose of the simplified schematic illustrations anddescriptions of FIGS. 1 and 2, the numerous valves, temperature sensors,electronic controllers and the like that may be employed and well knownto those of ordinary skill in the art of certain refinery operations arenot included. Further, accompanying components that are in conventionalrefinery operations including catalytic conversion processes such as,for example, air supplies, catalyst hoppers, and flue gas handling arenot depicted. However, operational components, such as those describedpreviously, may be added to the embodiments described in thisdisclosure.

It should further be noted that arrows in the drawings refer to transferlines which may serve to transfer steams between two or more systemcomponents. Additionally, arrows that connect to system componentsdefine inlets or outlets, or both, in each given system component. Thearrow direction corresponds generally with the major direction ofmovement of the materials of the stream contained within the physicaltransfer line signified by the arrow. Furthermore, arrows which do notconnect two or more system components signify a product stream whichexits the depicted system or a system inlet stream which enters thedepicted system. Product streams may be further processed inaccompanying chemical processing systems or may be commercialized as endproducts. System inlet streams may be streams transferred fromaccompanying chemical processing systems or may be non-processedfeedstock streams.

Reference will now be made in greater detail to various embodiments,some embodiments of which are illustrated in the accompanying drawings.Whenever possible, the same reference numerals will be used throughoutthe drawings to refer to the same or similar parts.

DETAILED DESCRIPTION

Generally, described in this disclosure are various embodiments ofsystems and methods for converting butene into propylene. Generally, theconversion system includes components which are operable to carry out amethod where a stream comprising butene in split into two portions,where the first portion undergoes a metathesis reaction and a crackingreaction to form propylene and ethylene. The second portion of thestream comprising butene is combined with a stream comprising ethylene.The combined stream comprising butene and ethylene is metathesized.Thus, with reference to the stream comprising butene, ametathesis/cracking reaction and a metathesis reaction are performed ina parallel system arrangement. The products of these two reactor units(that is, the metathesis/cracking product stream and the crackingproduct stream) may optionally be combined and components of the twostreams may be recovered by one or more separation processes. Forexample, a propylene stream may be recovered by at least partiallyseparating propylene from at least one of the metathesis/crackingproduct stream, the cracking product stream, or the mixture of the twostreams. Additionally, the stream comprising ethylene, which is combinedwith the second portion of the stream comprising butene can be a systemrecycle stream derived from a separation of ethylene from othercomponents of one or more of the product streams.

Furthermore, following the reactions of the first portion and secondportion of the stream comprising butene, the reaction product streamsmay be separated into multiple process streams, where some streams mayoptionally be recycled back into the system. Thus, the systems mayoperate with a single system inlet stream comprising at least about 50wt. % butene, such as raffinate streams created from a naphtha crackingprocess. The systems generally do not require a system inlet comprisingethylene, as the ethylene consumed in the reaction of the system is selfproduced from the metathesis reaction of the first portion of the butenestream.

As used in this disclosure, “transfer lines” may include pipes,conduits, channels, or other suitable physical transfer lines thatconnect by fluidic communication one or more system components to one ormore other system components. As used in this disclosure, a “systemcomponent” refers to any apparatus included in the system, such as, butnot limited to, separation units, reactors, heat transfer devices suchas heaters and heat exchangers, filters, impurities removal devices,combinations of each, and the like. A transfer line may generally carrya process stream between two or more system components. Generally, atransfer line may comprise multiple segments, where a “segment” of atransfer line includes one or more portions of a transfer line, suchthat a transfer line may comprise multiple transfer line segments.Generally, the chemical composition of a process stream in a particulartransfer line is similar or identical throughout the entire length ofthe transfer line. However, it should be appreciated that thetemperature, pressure, or other physical properties of a process streammay change through a transfer line, particularly in different transferline segments. Also, relatively minor compositional changes in a processstream may take place over the length of a transfer line, such as theremoval of an impurity. Also, sometimes the systems described in thisdisclosure are referred to as “butene conversion systems,” which refersto any system which at least partially converts butene into one or moreother chemical species. For example, in some embodiments, butene is atleast partially converted into propylene. As described in thisdisclosure, the butene conversion systems are suitable to processstreams comprising butene, including streams that are substantially freeof other alkenes (for example, ethylene, propene), into a productprocess stream comprising a significant amount of propylene. As used inthis disclosure, a stream or composition does “not substantiallycomprise” or “is substantially free” of a component when that componentis present in an amount of less than 0.1 wt. %.

As used in this disclosure, a “separation unit” refers to any separationdevice that at least partially separates one or more chemicals that aremixed in a process stream from one another. For example, a separationunit may selectively separate differing chemical species from oneanother, forming one or more chemical fractions. Examples of separationunits include, without limitation, distillation columns, flash drums,knock-out drums, knock-out pots, centrifuges, filtration devices, traps,scrubbers, expansion devices, membranes, solvent extraction devices, andthe like. It should be understood that separation processes described inthis disclosure may not completely separate all of one chemicalconsistent from all of another chemical constituent. It should beunderstood that the separation processes described in this disclosure“at least partially” separate different chemical components from oneanother, and that even if not explicitly stated, it should be understoodthat separation may include only partial separation. As used in thisdisclosure, one or more chemical constituents may be “separated” from aprocess stream to form a new process stream. Generally, a process streammay enter a separation unit and be divided, or separated, into two ormore process streams of desired composition. Further, in some separationprocesses, a “light fraction” and a “heavy fraction” may exit theseparation unit, where, in general, the light fraction stream has alesser boiling point than the heavy fraction stream.

As used in this disclosure, a “reactor” refers to a vessel in which oneor more chemical reactions may occur between one or more reactantsoptionally in the presence of one or more catalysts. For example, areactor may include a tank or tubular reactor configured to operate as abatch reactor, a continuous stirred-tank reactor (CSTR), or a plug flowreactor. Example reactors include packed bed reactors such as fixed bedreactors, and fluidized bed reactors. A reactor may comprise one or morecatalyst sections, such as catalyst beds, where a “section” is the areaof the reactor which houses a particular catalyst or group of multiplecatalysts. In another embodiment, separation and reactions may takeplace in a reactive separation unit.

As used in this disclosure, a “catalyst” refers to any substance whichincreases the rate of a specific chemical reaction. Catalysts describedin this disclosure may be utilized to promote various reactions, suchas, but not limited to, metathesis or cracking reactions, or both. Asused in this disclosure, a “metathesis catalyst” increases the rate of ametathesis reaction, and a “cracking catalyst” increases the rate of acracking reaction. As used in this disclosure “metathesis” generallyrefers to a chemical reaction where fragments of alkenes (olefins) areredistributed by the scission and regeneration of alkene bonds. Also, asused in this disclosure, “cracking” generally refers to a chemicalreaction where a molecule having carbon to carbon bonds is broken intomore than one molecule by the breaking of one or more of the carbon tocarbon bonds. The resulting cracked molecules may have combined the samenumber of carbon atoms as the original molecule prior to cracking.

Examples of metathesis catalysts and cracking catalysts are disclosed inco-pending Saudi Aramco U.S. Provisional Patent Application No.62/181,178 entitled “Dual Catalyst System for Propylene Production” andco-pending Saudi Aramco U.S. Provisional Patent Application No.62/181,129 entitled “Propylene Production Using a Mesoporous Silica FoamMetathesis Catalyst”, each of which are incorporated by reference intheir entirety in this disclosure. As noted it that disclosure, suitablemetathesis catalysts may include mesoporous silica catalysts impregnatedwith metal oxide. Suitable cracking catalysts may include mordeniteframework inverted (MFI) structured silica catalysts. The mesoporoussilica catalysts may include a pore size distribution of from about 2.5nm to about 40 nm and a total pore volume of at least about 0.600 cm³/g(cubic centimeters per gram). However, it should be understood that thesystems described in this disclosure may include any suitable metathesiscatalysts and cracking catalysts, such as commercially availablecatalysts or catalysts which are the subject of future discovery.

The suitable reaction conditions for metathesis and cracking reactionsdescribed in this disclosure may vary by the catalyst compositionsemployed. However, in some embodiments, the metathesis or crackingreactions, or both, may take place at temperatures from about 500° C.(degrees Celsius) to about 600° C. in atmospheric pressure.

As described in this disclosure, “butene” may include at least 1-butene,isobutene, cis-2-butene, trans-2-butene 2-methyl-2-butene,3-methyl-1-butene, 2-methyl-1-butene, and cyclobutene. Butene issometimes referred to as butylene, and the terms “butene” and “butylene”may be used interchangeably in this disclosure. As described in thisdisclosure, “pentene” may include at least 1-pentene, cis-2-pentene,trans-2-pentene, 4-methyl-trans-2-pentene, cyclopentene, and2-methyl-2-pentene. As described in this disclosure, “hexene” mayinclude at least trans-2-hexene, trans-3-hexene, cis-3-hexene, andcyclohexene. In this disclosure, certain chemicals may be referred to inshorthand notation, where C2 stands for ethane, C3 stands for propane,C4 stands for ethane, C5 stands for pentane, C6 stands for hexane, C3═stands for propylene (or propene), C4═ stands for butene (or butylene),C5═ stands for pentene, and C6═ stands for hexene.

It should be understood that when two or more process stream are “mixed”or “combined” when two or more lines intersect in the schematic flowdiagrams of FIGS. 1 and 2. Mixing or combining may also include mixingby directly introducing both streams into a like reactor, separationdevice, or other system component.

It should be understood that while the embodiments of FIGS. 1 and 2 mayhave varying mechanical apparatus or process stream compositions, orboth, these embodiments generally share many of the same systemcomponents and transfer lines. As such, processes which occur in likesystem components in the various embodiments of FIGS. 1 and 2 may besimilar or identical with one another. For example, the systemcomponents of FIGS. 1 and 2 marked with the same reference number mayperform similar or identical operations in the various embodiments. Someprocess streams in the embodiments of FIGS. 1 and 2 may comprise similaror identical compositions, while others may not. For clarity, thetransfer lines of the embodiments of FIGS. 1 and 2 have each been givendifferent reference numbers so that the composition of their containedstream may be easily identified. However, while some transfer lines maybe in like areas and have like functions in the various embodiments ofFIGS. 1 and 2, they may have substantially different compositions (suchas in cases where recycle streams are present or where recycle streamsreenter at differing system locations). Some process streams containedin like areas of FIGS. 1 and 2 may be similar or even identical in likeprocessing conditions (for example, like inlet stream composition). Forexample, the streams of transfer lines/segments such as, but not limitedto: 210 and 301A may be similar or substantially identical incomposition; 236 and 336 may be similar or substantially identical incomposition; 234 and 334 may be similar or substantially identical incomposition; 207 and 307 may be similar or substantially identical incomposition; 216 and 316 may be similar or substantially identical incomposition; and 206 and 406 may be similar or substantially identicalin composition. The Examples, as provided in this disclosure, furtherclarify the differences in stream compositions between the variousembodiments.

Referring now to the process-flow diagram of FIG. 1, in one embodiment,a butene conversion system 100 may include a metathesis/cracking reactor120 which comprises a metathesis catalyst section 122 and a crackingcatalyst section 124. Generally, a system inlet stream comprising buteneenters the butene conversion system 100 through transfer line 210. Thesystem inlet stream generally comprises at least butene, and mayoptionally comprise other chemical species such as butane. For example,the system inlet stream may comprise at least about 20 wt. %, 30 wt. %,40 wt. %, 50 wt. %, 55 wt. %, 60 wt. %, 65 wt. %, or even at least about70 wt. % butene. The system inlet stream of transfer line 210 maycomprise at least about 15 wt. %, 20 wt. %, 25 wt. %, 30 wt. %, or evenat least about 35 wt. % butane, and may comprise from 0 wt. % to about10 wt. %, 8 wt. %, 2 wt. %, or 4 wt. % ethylene, or may notsubstantially comprise ethylene. The system inlet stream in transferline 210 is combined with a recycle stream in transfer line 212 to forma mixed stream present in transfer line 201. The mixed stream is passedthrough transfer line segments 201A, 201B, 201C, and 201D, and is splitinto two mixed stream portions located in transfer line segments 201Eand 201F. The mixed stream in transfer line segment 201E is injectedinto the metathesis/cracking reactor 120.

In embodiments, the recycle stream of transfer line 212 may comprisebutene and butane. For example, the recycle stream of transfer line 212may comprise at least about 5 wt. %, 10 wt. %, 15 wt. %, or even atleast about 20 wt. % butene, and may comprise at least about 50 wt. %,60 wt. %, 70 wt. %, or even greater than about 80 wt. % butane. Therecycle stream of transfer line 212 may comprise at least about 80 wt.%, 90 wt. % or even at least about 95 wt. % of butane and butene. Themixed stream of transfer line 201 may comprise butane and butene. Forexample, the mixed stream of transfer line 201 may comprise at leastabout 5 wt. %, 10 wt. %, 15 wt. %, 20 wt %, 25 wt. %, 30 wt. %, or evenat least about 35 wt. % butene, and may comprise at least about 40 wt.%, 50 wt. %, 60 wt. %, 70 wt. %, or even greater than about 80 wt. %butane. The mixed stream of transfer line 201 may comprise at leastabout 80 wt. %, 90 wt. % or even at least about 95 wt. % of thecombination of butane and butene.

In one embodiment, the mixed stream may be split in a first mixed streamportion in transfer line segment 201E and a second mixed stream portionin transfer line segment 201F where the ratio of the mass flowrate ofthe first mixed stream portion to the flowrate of the second mixedstream portion is between about 2:1 and 3:1, 1.5:1 and 4:1, or 1:1 to6:1.

The mixed stream may be processed by one or more system components priorto being split into the streams of segments 201E and 201F. In someembodiments, the transfer line 201 may comprise several segments(depicted as 201A, 201B, 201C, and 201D) which may be separated bysystem components such as an impurities removal device 110, heattransfer device 112, and heat transfer device 114. The impuritiesremoval device 110 may remove oxygenates present in the mixed stream. Inone embodiment, the impurities removal device comprises a catalytic bed.Heat transfer device 112 may be a heat exchanger that serves to elevatethe temperature of the mixed stream by exchanging energy with the streampresent in transfer line 203A. Heat transfer device 114 may be a heaterthat serves to further heat the mixed stream. It should be understoodthat the impurities removal device 110, heat transfer device 112, andheat transfer device 114 are optional components in the buteneconversion system 100. It should be understood that all streams locatedin the various segments of transfer line 201 (that is, 201A, 201B, 201C,201D, 201E, and 201F) are considered portions of the mixed stream, eventhough the chemical composition, temperature, or other properties of thesystem inlet stream may be different in the various segments 201A, 201B,201C, 201D, 201E, and 201F.

Still referring to FIG. 1, the metathesis catalyst section 122 ispositioned generally upstream of the cracking catalyst section 124, thatis, the cracking catalyst section 124 is positioned generally downstreamof the metathesis catalyst section 122. The portion of the mixed streamof segment 201E enters the metathesis/cracking reactor 120 and undergoesa metathesis reaction in the metathesis catalyst section 122 to form ametathesis-reaction product. Following the metathesis reaction, themetathesis-reaction product is cracked in a cracking reaction in thecracking catalyst section 124. The cracking reaction forms acracking-reaction product. Generally, the reactants that undergocracking or metathesis, or both, intimately intermingle with therespective catalysts during reaction.

As used in this disclosure, a “metathesis-reaction product” refers tothe entire product mixture resulting from the metathesis reaction,including any portion of the metathesis-product stream which does notundergo metathesis. Additionally, as used in this disclosure“cracking-reaction product” refers to the entire product mixtureresulting from the cracking reaction, including any portion of thecracking-product mixture which does not undergo cracking.

The cracking-reaction product is passed out of the metathesis/crackingreactor 120 in a cracking-reaction product stream via transfer line 232.The cracking-reaction product of transfer line 232 may comprise,consist, or consist essentially of a mixture of alkanes and alkenes,including, but not limited to, one or more of ethylene, propylene,butene, pentene, hexene, heptene, ethane, propane, butane, pentane,hexane, and heptane. The cracking-reaction product may comprise at leastabout 2 wt. %, 4 wt. %, 6 wt. %, 8 wt. %, 10 wt. %, 12 wt. %, 14 wt. %,16 wt. %, 18 wt. %, 20 wt. %, 22 wt. %, 24 wt. %, 26 wt. %, 28 wt. %, oreven at least about 30 wt. % propylene.

The portion of the mixed stream that is present in segment 201F iscombined with an ethylene recycle stream present in transfer line 234.The ethylene recycle stream may be generated from the separation processof separation unit 130, which will be described in this disclosure.Generally, the ethylene recycle stream of transfer line 234 comprises atleast about 50 wt. %, 60 wt. %, 70 wt. %, 80 wt. %, 90 wt. %, 95 wt. %,96 wt. %, 97 wt. %, 98 wt. %, or even at least about 99 wt. % ethylene.The combination of the mixed stream of segment 201F and the ethylenerecycle stream of transfer line 234 forms a butene/ethylene mixed streampresent in transfer line 238.

Still referring to FIG. 1, the metathesis reactor 140 comprises ametathesis catalyst section 141, such as a metathesis catalyst bed. Themetathesis reactor 140 and the metathesis/cracking reactor 120 arearranged in parallel relative to the mixed stream of transfer line 201.The butene/ethylene stream from transfer line 238 enters the metathesisreactor 140 and undergoes a metathesis reaction in the metathesiscatalyst section 141 to form a metathesis-reaction product. Themetathesis-reaction product may be passed out of the metathesis reactorin a metathesis-reaction product stream via transfer line 240. Themetathesis-reaction product of transfer line 240 may comprise, consist,or consist essentially of a mixture of alkanes and alkenes, including,but not limited to, one or more of ethylene, propylene, butene, pentene,hexene, heptene, ethane, propane, butane, pentane, hexane, and heptane.The metathesis-reaction product of transfer line 240 may comprise atleast about 2 wt. %, 4 wt. %, 6 wt. %, 8 wt. %, 10 wt. %, 12 wt. %, 14wt. %, 16 wt. %, 18 wt. %, 20 wt. %, 22 wt. %, 24 wt. %, 26 wt. %, 28wt. %, or even at least about 30 wt. % propylene.

The metathesis-reaction product stream of transfer line 240 may becombined with the cracking-reaction product stream of transfer line 232to form a mixed product stream of transfer line 203 (including segments203A and 203B). In one embodiment, as shown in FIG. 1, the mixed productstream of transfer line 203 may exchange heat with the mixed stream ofsegment 201B via heat transfer device 112.

The mixed-reaction product stream of transfer line segment 203B may beseparated into one or more streams having desired compositions.Generally, a product stream comprising propylene, such as shown intransfer line 207 in FIG. 1, may be formed by separating propylene inthe mixed-reaction product stream. Additionally, the ethylene recyclestream of transfer line 234 may be separated from the mixed-reactionproduct stream of transfer line segment 203B. The propylene productstream may comprise at least about 50 wt. %, 60 wt. %, 70 wt. %, 80 wt.%, 90 wt. %, 95 wt. %, 96 wt. %, 97 wt. %, 98 wt. %, or even at leastabout 99 wt. % propylene. It should be understood that a wide variety ofseparation processes may be utilized to produce the product streamcomprising propylene.

In one embodiment, as shown in FIG. 1, the mixed-reaction product streamof transfer line segment 203B may be introduced to one or moreseparation units, such as separation unit 130. The mixed reactionproduct may enter separation unit 130 where light constituents, such andethane and ethylene, may be removed. Light constituents such as ethylenemay be purged from the butene conversion system 100 via transfer line236 or may be utilized as the ethylene recycle stream via transfer line234. The streams contained in transfer line 234 and transfer line 236may comprise, consist, or consist essentially of ethylene. For example,the stream of transfer line 204 or transfer line 205, or both, maycomprise at least about 50 wt. %, 60 wt. %, 70 wt. %, 80 wt. %, 90 wt.%, 95 wt. %, 96 wt. %, 97 wt. %, 98 wt. %, or even at least about 99 wt.% ethylene. The heavy fraction from separation unit 130 may be passedout of separation unit 130 via transfer line 206. The stream of line 206may comprise a mixture of alkanes and alkenes, including, but notlimited to, one or more of propylene, butene, pentene, hexene, heptene,ethane, propane, butane, pentane, hexane, and heptane. The stream oftransfer line 206 may enter separation unit 140 where propylene isseparated from other constituents. The light fraction (that is,propylene) may exit the separation unit 140 via transfer line 207 as apropylene product stream. The propylene product stream contained intransfer line 207 may comprise, consists, or consist essentially ofpropylene. For example, the stream of transfer line 204 or transfer line205, or both, may comprise at least about 50 wt. %, 60 wt. %, 70 wt. %,80 wt. %, 90 wt. %, 95 wt. %, 96 wt. %, 97 wt. %, 98 wt. %, or even atleast about 99 wt. % propylene. The heavy fraction from separation unit140 may be passed out of separation unit 140 via transfer line 208. Thestream of line 208 may comprise a mixture of alkanes and alkenes,including, but not limited to, one or more of butene, pentene, hexene,heptene, ethane, propane, butane, pentane, hexane, and heptane.

The stream of transfer line 208 may be injected into separation unit 150where one or more fractions may be separated from one another. In oneembodiment, a bottoms fraction may exit separation unit 150 in a streamcontained in transfer line 214. The stream of transfer line 214 maycomprise one or more of butene, pentene, pentane, hexene, heptene, andbutane. The top fraction, which comprises primarily butene and butane,may exit separation unit 150 in the recycle stream contained in transferline 212. A portion of the recycle stream contained in transfer line 212may be purged from the system 100 via transfer line 216. The remainingportion may be recycled into the system 100 by combining the recyclestream of transfer line 212 with the system inlet stream of transferline 210. In embodiments, the recycle stream of transfer line 212 maycomprise at least about 5 wt. %, 10 wt. %, 15 wt. %, 20 wt. %, 25 wt. %,30 wt. %, or even at least about 35 wt. % butene, and may comprise atleast about 40 wt. %, 50 wt. %, 60 wt. %, 70 wt. %, or even greater thanabout 80 wt. % butane. The recycle stream of transfer line 512 maycomprise at least about 80 wt. %, 90 wt. %, or even at least about 95wt. % of butane and butene.

FIG. 2 depicts an embodiment which is similar to that of FIG. 1, but therecycle stream comprising butene (shown in transfer line 312) mixes intoa different portion of the butene conversion system 200. As shown inFIG. 2, the butene conversion system 200 comprises a recycle stream intransfer line 312 (including segments 312A and 312B) which is combinedwith the streams of transfer line segment 301F and transfer line 334. Inembodiments, the recycle stream of transfer line 312 may comprise atleast about 5 wt. %, 10 wt. %, 15 wt. %, 20 wt. %, 25 wt. %, 30 wt. %,or even at least about 35 wt. % butene, and may comprise at least about40 wt. %, 50 wt. %, 60 wt. %, 70 wt. %, or even greater than about 80wt. % butane. The recycle stream of transfer line 512 may comprise atleast about 80 wt. %, 90 wt. %, or even at least about 95 wt. % ofbutane and butene.

In the embodiment of FIG. 2, since the recycle stream of transfer line312 does not combine with the inlet stream 301, the process streamentering the metathesis/cracking reactor 120 is the inlet stream oftransfer line 301. The cracking-reaction product of transfer line 332may comprise, consist, or consist essentially of a mixture of alkanesand alkenes, including, but not limited to, one or more of ethylene,propylene, butene, pentene, hexene, heptene, ethane, propane, butane,pentane, hexane, and heptane. The cracking-reaction product may compriseat least about 2 wt. %, 4 wt. %, 6 wt. %, 8 wt. %, 10 wt. %, 12 wt. %,14 wt. %, 16 wt. %, 18 wt. %, 20 wt. %, 22 wt. %, 24 wt. %, 26 wt. %, 28wt. %, or even at least about 30 wt. % propylene.

It should be appreciated the butene conversion systems described in thisdisclosure do not require a recycle stream comprising butene (as ispresent in the transfer lines of 212 in the embodiment of FIG. 1 andtransfer line 312 in the embodiment of FIG. 2). For example, inembodiments, the process stream of transfer line 208 may be expelledfrom the butene conversion system. In other embodiments, the recyclestreams of FIGS. 1 and 2 may be employed in the same system.

Referring to the embodiments of FIGS. 1 and 2, it should be appreciatedthat the flowrate of the process stream of transfer line 236 and 336 maybe controlled based on the desire to utilize the ethylene of transferlines 236 and 336 in outside processes or sale for commercial gain. Forexample, if ethylene is commercially marketable relative to propylene,its flowrate may be increased. Additionally, it should be appreciatedthat other system streams may be changed in reaction to a change in theflowrate of transfer lines 236 and 336. For example, if the flowrate oftransfer line 236 or 336 is increased, less ethylene will be availablefor the metathesis reaction in reactor 140. Therefore, in someembodiments, the amount of propylene supplied to the metathesis reactor140 should be reduced by reducing the flowrate of at least transfer linesegment 201F, 301F, or 312A, or each.

In another embodiment, the butene conversion systems described in thisdisclosure may comprise multiple reactors in series in place of ametathesis/cracking reactor 120. In some embodiments, it may beadvantageous to utilize reactors in series when the metathesis reactionand cracking reaction are performed at different conditions (such astemperature or pressure). In such embodiments, the system may comprise ametathesis reactor which comprises a metathesis catalyst section, suchas a metathesis catalyst bed, and a cracking reactor which comprises acracking catalyst section, such as a cracking catalyst bed. In such anembodiment, the metathesis reactor and the cracking reactor are arrangedin series where the metathesis reactor is positioned generally upstreamof the cracking reactor, that is, the cracking reactor is positionedgenerally downstream of the metathesis reactor. With reference to FIG.1, an inlet stream from segment 201E enters a metathesis reactor andundergoes a metathesis reaction to form a metathesis-reaction product.The metathesis-reaction product may then be passed out of the metathesisreactor in a metathesis-reaction product stream. The metathesis-reactionproduct stream then enters a cracking reactor and is cracked in acracking reaction. The cracking reaction forms a cracking-reactionproduct. The cracking-reaction product is passed out of the crackingreactor in a cracking-reaction product stream, similar to the stream 232of FIG. 1. Examples of separate metathesis and cracking reactorsarranged in series are available in co-pending Saudi Aramco U.S.Provisional Patent Application No. 62/181,052 entitled “Systems andMethods for Producing Propylene”, which is incorporated by reference inits entirety in this disclosure. Such dual reactor systems could beintegrated into the systems of FIGS. 1 and 2 by replacing reactor 120with two reactors in series.

Generally, a stream containing butane and butene, suitable as the inletstream in the embodiments described in this disclosure, may be producedfrom refining operations. This stream containing butane and butene maybe separated into fractions to form a first raffinate, second raffinate,and third raffinate. In one embodiment, the system inlet stream may be araffinate stream from an olefin refining system, such as a conventionalrefinery. The stream produced from the refining operation may generallycomprise C4 alkanes and alkenes, including butanes, butenes, andbutadienes. A “first raffinate” may be produced by separating1,3-butadiene from the other C4 constituents in the stream. The firstraffinate may comprise isobutylene, cis-2-butene, and trans-2-butene.For example, the first raffinate may comprise, or consist essentiallyof, from about 40 wt. % to about 50 wt. %, from about 35 wt. % to about55 wt. %, or from about 30 wt. % to about 60 wt. % of isobutene and fromabout 30 wt. % to about 35 wt. %, from about 25 wt. % to about 40 wt. %,or from about 20 wt. % to about 45 wt. % of the sum of cis-2-butene andtrans-2-butene. A “second raffinate” may be produced by separatingisobutylene from the other C4 constituents of the first raffinate. Forexample, the second raffinate may comprise, or consist essentially of,from about 50 wt. % to about 60 wt. %, from about 45 wt. % to about 65wt. %, or from about 40 wt. % to about 70 wt. % of the sum ofcis-2-butene and trans-2-butene, from about 10 wt. % to about 15 wt. %,from about 5 wt. % to about 20 wt. %, or from about 0 wt. % to about 25wt. % of 1-butene, and from about 15 wt. % to about 25 wt. %, from about10 wt. % to about 30 wt. %, or from about 5 wt. % to about 35 wt. % ofbutane. The inlet stream of the systems described herein may besubstantially free of isobutene, and may consist essentially of2-butenes and n-butanes.

EXAMPLES

The various embodiments of methods and systems for the cracking of alight fuel fraction and a heavy fuel fraction by fluidized catalyticcracking will be further clarified by the following examples. Theexamples are illustrative in nature, and should not be understood tolimit the subject matter of the present disclosure.

Example 1

The systems of FIG. 1 was computer modeled using Aspen Plus®(commercially available from AspenTech). The subsequent tables (Tables1-4) depict the stream compositions and flowrates, as well as thermalproperties for selected streams. The reaction rates supplied for thesimulation were representative of experimental reaction rates for themetathesis catalyst W-SBA-15 and the cracking catalyst MFI-2000, asdescribed in Examples 1, 3, and 6 of co-pending Saudi Aramco U.S.Provisional Patent Application No. 62/181,178 entitled “Dual CatalystSystem for Propylene Production”. A system inlet stream of 35 wt. %cis-2-butene, 35 wt. % trans-2-butene, and 30 wt. % n-butane was usedfor the model. The stream numbers corresponds with the stream or streamsegment shown in FIG. 1. Simulations were run for 100% efficiency and80% efficiency. Data for the simulations is provided on a weight basisand a mole basis for each simulation. Specifically, Table 1 depicts datafor a simulation of the system of FIG. 1 with 100% efficiency and showscomponents on a mass basis. Table 2 depicts data for a simulation of thesystem of FIG. 1 with 100% efficiency and shows components on a molebasis. Table 3 depicts data for a simulation of the system of FIG. 1with 80% efficiency and shows components on a mass basis. Table 4depicts data for a simulation of the system of FIG. 1 with 80%efficiency and shows components on a mole basis. Additionally, FIG. 3depicts a bar graph displaying the product distribution of the system ofFIG. 1 as shown in Table 1 where, on the bar graph, “Propylene”corresponds with the stream of transfer line 207, “Light Purge”corresponds with the stream of transfer line 236, “C4 Purge” correspondswith the stream of transfer line 216, and “C5+Heavy” corresponds withthe stream of transfer line 214.

TABLE 1 FIG. 1 with 100% efficiency in wt. % Stream Number 210201A/B/C/D 201E 232 201F 238 240 203A/B Mole Flow, 100.0 277.5 194.3214.7 83.3 134.6 134.6 349.3 kmol/hr Mass Flow, 5670 15918 11143 111434775 6221 6221 17364 kg/hr Volumn Flow 6750 10562 7393 10556 3169 41999091 28.4 m³/hr Enthalpy, MW 0.6 −3.6 −2.5 −1.3 −1.1 −0.7 0.8 −5.5 MW,g/mol 56.7 57.4 57.4 51.9 57.4 46.2 46.2 49.7 Density, kg/m³ 0.84 1.511.51 1.06 1.51 1.48 0.68 610.5 COMPONENTS, wt % Ethylene 0.0% 0.0% 0.0%5.6% 0.0% 23.0% 15.7% 9.2% Propylene 0.0% 0.2% 0.2% 15.9% 0.2% 0.4%22.9% 18.4% Propane 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 1-Butene0.0% 2.3% 2.3% 2.3% 2.3% 1.8% 2.6% 2.4% Isobutene 0.0% 3.9% 3.9% 4.8%3.9% 3.0% 3.0% 4.2% cis-2-butene 35.0% 14.5% 14.5% 2.3% 14.5% 11.1% 2.6%2.4% trans-2-butene 35.0% 15.1% 15.1% 2.7% 15.1% 11.6% 3.1% 2.9%n-Butane 30.0% 63.9% 63.9% 63.9% 63.9% 49.1% 49.1% 58.6% 1-Pentene 0.0%0.0% 0.0% 0.1% 0.0% 0.0% 0.0% 0.1% cis-2-Pentene 0.0% 0.0% 0.0% 0.2%0.0% 0.0% 0.3% 0.2% trans-2-Pentene 0.0% 0.0% 0.0% 0.3% 0.0% 0.0% 0.6%0.4% 2-Methy-2- 0.0% 0.0% 0.0% 0.8% 0.0% 0.0% 0.0% 0.5% butene3-Methy-1- 0.0% 0.0% 0.0% 0.1% 0.0% 0.0% 0.0% 0.1% butene 2-Methy-1-0.0% 0.0% 0.0% 0.4% 0.0% 0.0% 0.0% 0.3% butene Sum of hexenes, 0.0% 0.0%0.0% 0.5% 0.0% 0.0% 0.0% 0.3% hexanes, and heavier Total mol % 100.0%100.0% 100.0% 100.0% 100.0% 100.0% 100.0% 100.0% Stream Number 236 234206 207 208 216 212 214 Mole Flow, 5.7 51.4 292.2 75.8 216.4 19.7 177.519.1 kmol/hr Mass Flow, 161 1446 15757 3197 12561 1139 10248 1174 kg/hrVolumn Flow 0.4 3.3 34.6 6.7 27.5 2.3 20.9 2.4 m³/hr Enthalpy, MW 0.00.4 −4.9 0.1 −5.0 −0.5 −4.3 −0.4 MW, g/mol 28.1 28.1 53.9 42.2 58.0 57.757.7 61.3 Density, kg/m³ 438.1 438.1 455.8 477.9 456.5 490.8 490.8 495.8COMPONENTS, wt % Ethylene 99.0% 99.0% 0.1% 0.3% 0.0% 0.0% 0.0% 0.0%Propylene 1.0% 1.0% 20.2% 98.5% 0.3% 0.3% 0.3% 0.0% Propane 0.0% 0.0%0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 1-Butene 0.0% 0.0% 2.6% 0.3% 3.2% 3.6%3.6% 0.2% Isobutene 0.0% 0.0% 4.6% 0.6% 5.6% 6.1% 6.1% 0.3% cis-2-butene0.0% 0.0% 2.6% 0.0% 3.3% 3.1% 3.1% 5.2% trans-2-butene 0.0% 0.0% 3.2%0.0% 4.0% 4.1% 4.1% 3.0% n-Butane 0.0% 0.0% 64.6% 0.3% 81.0% 82.7% 82.7%63.7% 1-Pentene 0.0% 0.0% 0.1% 0.0% 0.1% 0.0% 0.0% 1.1% cis-2-Pentene0.0% 0.0% 0.2% 0.0% 0.3% 0.0% 0.0% 3.1% trans-2-Pentene 0.0% 0.0% 0.5%0.0% 0.6% 0.0% 0.0% 6.1% 2-Methy-2- 0.0% 0.0% 0.6% 0.0% 0.7% 0.0% 0.0%7.3% butene 3-Methy-1- 0.0% 0.0% 0.1% 0.0% 0.1% 0.0% 0.0% 0.7% butene2-Methy-1- 0.0% 0.0% 0.3% 0.0% 0.4% 0.0% 0.0% 3.8% butene Sum ofhexenes, 0.0% 0.0% 0.5% 0.0% 0.5% 0.0% 0.0% 5.4% hexanes, and heavierTotal mol % 100.0% 100.0% 100.0% 100.0% 100.0% 100.0% 100.0% 100.0%

TABLE 2 FIG. 1 with 100% efficiency in mol % Stream Number 210201A/B/C/D 201E 232 201F 238 240 203A/B Mole Flow, 100.0     277.5    194.3     214.7     83.3    134.6     134.6     349.3     kmol/hr MassFlow, 5670    15918     11143     11143      4775     6221     6221    17364      kg/hr Volumn Flow 6750    10562     7393     10556     3169     4199     9091     28.4    m³/hr Enthalpy, MW 0.6  −3.6   −2.5  −1.3   −1.1   −0.7   0.8  −5.5   MW, g/mol 56.7    57.4    57.4   51.9    57.4    46.2    46.2    49.7    Density, kg/m³ 0.84  1.51  1.51 1.06  1.51  1.48  0.68  610.5     COMPONENTS, mol % Ethylene 0.0% 0.0%0.0% 10.3%  0.0% 37.9%  25.9%  16.3%  Propylene 0.0% 0.2% 0.2% 19.6% 0.2% 0.4% 25.1%  21.7%  Propane 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0%1-Butene 0.0% 2.3% 2.3% 2.1% 2.3% 1.4% 2.1% 2.1% Isobutene 0.0% 4.0%4.0% 4.4% 4.0% 2.5% 2.5% 3.7% cis-2-butene 35.4%  14.8%  14.8%  2.1%14.8%  9.1% 2.1% 2.1% trans-2-butene 35.4%  15.4%  15.4%  2.5% 15.4% 9.5% 2.6% 2.6% n-Butane 29.3%  63.1%  63.1%  57.1%  63.1%  39.0%  39.0% 50.1%  1-Pentene 0.0% 0.0% 0.0% 0.1% 0.0% 0.0% 0.0% 0.1% cis-2-Pentene0.0% 0.0% 0.0% 0.1% 0.0% 0.0% 0.2% 0.2% trans-2-Pentene 0.0% 0.0% 0.0%0.2% 0.0% 0.0% 0.4% 0.3% 2-Methyl-2- 0.0% 0.0% 0.0% 0.6% 0.0% 0.0% 0.0%0.4% butene 3-Methyl-1- 0.0% 0.0% 0.0% 0.1% 0.0% 0.0% 0.0% 0.0% butene2-Methyl-1- 0.0% 0.0% 0.0% 0.3% 0.0% 0.0% 0.0% 0.2% butene Sum of 0.0%0.0% 0.0% 0.3% 0.0% 0.0% 0.0% 0.0% hexenes, hexanes, and heavier Totalmol % 100.0%  100.0%  100.0%  100.0%  100.0%  100.0%  100.0%  100.0% Total mol % 200%    200%    200%    200%    200%    200%    200%   200%    Stream Number 236 234 206 207 208 216 212 214 Mole Flow, 5.751.4 292.2 75.8 216.4 19.7 177.5 19.1 kmol/hr Mass Flow, 161 1446 157573197 12561 1139 10248 1174 kg/hr Volumn Flow 0.4 3.3 34.6 6.7 27.5 2.320.9 2.4 m³/hr Enthalpy, MW 0.0 0.4 −4.9 0.1 −5.0 −0.5 −4.3 −0.4 MW,g/mol 28.1 28.1 53.9 42.2 58.0 57.7 57.7 61.3 Density, kg/m³ 438.1 438.1455.8 477.9 456.5 490.8 490.8 495.8 COMPONENTS, mol % Ethylene 99.3%99.3% 0.1% 0.4% 0.0% 0.0% 0.0% 0.0% Propylene 0.7% 0.7% 25.9% 98.7% 0.3%0.4% 0.4% 0.0% Propane 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 1-Butene0.0% 0.0% 2.5% 0.2% 3.4% 3.7% 3.7% 0.2% Isobutene 0.0% 0.0% 4.4% 0.5%5.8% 6.3% 6.3% 0.3% cis-2-butene 0.0% 0.0% 2.5% 0.0% 3.4% 3.2% 3.2% 5.6%trans-2-butene 0.0% 0.0% 3.1% 0.0% 4.1% 4.2% 4.2% 3.2% n-Butane 0.0%0.0% 59.9% 0.2% 80.8% 82.2% 82.2% 67.2% 1-Pentene 0.0% 0.0% 0.1% 0.0%0.1% 0.0% 0.0% 1.0% cis-2-Pentene 0.0% 0.0% 0.2% 0.0% 0.2% 0.0% 0.0%2.7% trans-2-Pentene 0.0% 0.0% 0.4% 0.0% 0.5% 0.0% 0.0% 5.4% 2-Methyl-2-0.0% 0.0% 0.4% 0.0% 0.6% 0.0% 0.0% 6.4% butene 3-Methyl-1- 0.0% 0.0%0.1% 0.0% 0.1% 0.0% 0.0% 0.6% butene 2-Methyl-1- 0.0% 0.0% 0.2% 0.0%0.3% 0.0% 0.0% 3.3% butene Sum of 0.0% 0.0% 0.1% 0.0% 0.3% 0.0% 0.0%3.8% hexenes, hexanes, and heavier Total mol % 100.0% 100.0% 100.0%100.0% 100.0% 100.0% 100.0% 100.0%

TABLE 3 FIG. 1 with 80% efficiency in wt. % Stream Number 210 201A 201E232 201F 238 240 203A/B Mole Flow, 100.0 322.4 225.7 151.6 96.7 121.3151.6 396.8 kmol/hr Mass Flow, 5669.7 18487.7 12941.4 7091.3 5546.35673.0 7091.3 20032.7 kg/hr Volumn Flow 6749.8 11369.4 7958.6 9280.63410.8 3526.3 9280.6 32.6 m³/hr Enthalpy, MW 0.6 −4.4 −3.1 0.6 −1.3 −0.70.6 −6.4 MW, g/mol 56.7 57.3 57.3 46.8 57.3 46.8 46.8 50.5 Density,kg/m³ 0.84 1.63 1.63 0.76 1.63 1.61 0.76 614.74 COMPONENTS, mol %Ethylene 0.0% 0.0% 0.0% 26.2% 0.0% 36.0% 26.2% 15.3% Propylene 0.0% 0.2%0.2% 20.5% 0.2% 0.4% 20.5% 18.0% Propane 0.0% 0.0% 0.0% 0.0% 0.0% 0.0%0.0% 0.0% 1-Butene 0.0% 2.4% 2.4% 2.2% 2.4% 1.5% 2.2% 2.2% Isobutene0.0% 4.0% 4.0% 2.6% 4.0% 2.6% 2.6% 3.7% cis-2-butene 35.4% 15.2% 15.2%3.8% 15.2% 9.7% 3.8% 4.3% trans-2-butene 35.4% 16.0% 16.0% 4.4% 16.0%10.2% 4.4% 4.8% n-Butane 29.3% 62.1% 62.1% 39.6% 62.1% 39.6% 39.6% 50.5%1-Pentene 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.1% cis-2-Pentene 0.0%0.0% 0.0% 0.2% 0.0% 0.0% 0.2% 0.1% trans-2-Pentene 0.0% 0.0% 0.0% 0.4%0.0% 0.0% 0.4% 0.3% 2-Methyl-2- 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.3%butene 3-Methyl-1- 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% butene2-Methyl-1- 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.2% butene Sum ofhexenes, 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% hexanes, and heavierTotal mol % 100.0% 100.0% 100.0% 100.0% 100.0% 100.0% 100.0% 100.0%Stream Number 236 234 206 207 208 216 212 214 Mole Flow, 6.1 54.9 335.871.2 264.6 24.7 222.4 17.5 kmol/hr Mass Flow, 171.7 1545.0 18316.13000.8 15315.3 1424.2 12818.0 1073.1 kg/hr Volumn Flow 0.4 3.5 40.3 6.333.4 2.9 26.0 2.2 m³/hr Enthalpy, MW 0.0 0.4 −5.7 0.1 −5.8 −0.6 −5.1−0.3 MW, g/mol 28.1 28.1 54.5 42.2 57.9 57.6 57.6 61.4 Density, kg/m³438.07 438.09 454.35 477.91 457.93 492.34 492.34 498.92 COMPONENTS, mol% Ethylene 99.3% 99.3% 0.1% 0.4% 0.0% 0.0% 0.0% 0.0% Propylene 0.7% 0.7%21.1% 98.7% 0.3% 0.3% 0.3% 0.0% Propane 0.0% 0.0% 0.0% 0.0% 0.0% 0.0%0.0% 0.0% 1-Butene 0.0% 0.0% 2.6% 0.2% 3.3% 3.5% 3.5% 0.2% Isobutene0.0% 0.0% 4.4% 0.4% 5.5% 5.8% 5.8% 0.2% cis-2-butene 0.0% 0.0% 5.1% 0.0%6.4% 6.1% 6.1% 11.3% trans-2-butene 0.0% 0.0% 5.7% 0.0% 7.2% 7.3% 7.3%5.2% n-Butane 0.0% 0.0% 59.7% 0.2% 75.7% 76.9% 76.9% 57.8% 1-Pentene0.0% 0.0% 0.1% 0.0% 0.1% 0.0% 0.0% 1.0% cis-2-Pentene 0.0% 0.0% 0.2%0.0% 0.2% 0.0% 0.0% 3.1% trans-2-Pentene 0.0% 0.0% 0.3% 0.0% 0.4% 0.0%0.0% 6.1% 2-Methyl-2- 0.0% 0.0% 0.4% 0.0% 0.4% 0.0% 0.0% 6.7% butene3-Methyl-1- 0.0% 0.0% 0.1% 0.0% 0.1% 0.0% 0.0% 0.7% butene 2-Methyl-1-0.0% 0.0% 0.2% 0.0% 0.3% 0.0% 0.0% 3.5% butene Sum of hexenes, 0.0% 0.0%0.0% 0.0% 0.1% 0.0% 0.0% 4.1% hexanes, and heavier Total mol % 100.0%100.0% 100.0% 100.0% 100.0% 100.0% 100.0% 100.0%

TABLE 4 FIG. 1 with 80% efficiency in mol % Stream Number 210 201A 201E232 201F 238 240 203A/B Mole Flow, 100.0 322.4 225.7 151.6 96.7 121.3151.6 396.8 kmol/hr Mass Flow, 5669.7 18487.7 12941.4 7091.3 5546.35673.0 7091.3 20032.7 kg/hr Volumn Flow 6749.8 11369.4 7958.6 9280.63410.8 3526.3 9280.6 32.6 m³/hr Enthalpy, MW 0.6 −4.4 −3.1 0.6 −1.3 −0.70.6 −6.4 MW, g/mol 56.7 57.3 57.3 46.8 57.3 46.8 46.8 50.5 Density,kg/m³ 0.84 1.63 1.63 0.76 1.63 1.61 0.76 614.74 COMPONENTS, wt %Ethylene 0.0% 0.0% 0.0% 15.7% 0.0% 21.6% 15.7% 8.5% Propylene 0.0% 0.1%0.1% 18.4% 0.1% 0.3% 18.4% 15.0% Propane 0.0% 0.0% 0.0% 0.0% 0.0% 0.0%0.0% 0.0% 1-Butene 0.0% 2.4% 2.4% 2.7% 2.4% 1.8% 2.7% 2.5% Isobutene0.0% 3.9% 3.9% 3.1% 3.9% 3.1% 3.1% 4.1% cis-2-butene 35.0% 14.8% 14.8%4.6% 14.8% 11.6% 4.6% 4.8% trans-2-butene 35.0% 15.7% 15.7% 5.2% 15.7%12.3% 5.2% 5.3% n-Butane 30.0% 63.0% 63.0% 49.3% 63.0% 49.3% 49.3% 58.1%1-Pentene 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.1% cis-2-Pentene 0.0%0.0% 0.0% 0.3% 0.0% 0.0% 0.3% 0.2% trans-2-Pentene 0.0% 0.0% 0.0% 0.6%0.0% 0.0% 0.6% 0.4% 2-Methy-2- 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.4%butene 3-Methy-1- 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.1% butene2-Methy-1- 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.2% butene Sum ofhexenes, 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.3% hexanes, and heavierTotal mol % 100.0% 100.0% 100.0% 100.0% 100.0% 100.0% 100.0% 100.0%Stream Number 236 234 206 207 208 216 212 214 Mole Flow, 6.1 54.9 335.871.2 264.6 24.7 222.4 17.5 kmol/hr Mass Flow, 171.7 1545.0 18316.13000.8 15315.3 1424.2 12818.0 1073.1 kg/hr Volumn Flow 0.4 3.5 40.3 6.333.4 2.9 26.0 2.2 m³/hr Enthalpy, MW 0.0 0.4 −5.7 0.1 −5.8 −0.6 −5.1−0.3 MW, g/mol 28.1 28.1 54.5 42.2 57.9 57.6 57.6 61.4 Density, kg/m³438.07 438.09 454.35 477.91 457.93 492.34 492.34 498.92 COMPONENTS, wt %Ethylene 99.0% 99.0% 0.0% 0.3% 0.0% 0.0% 0.0% 0.0% Propylene 1.0% 1.0%16.3% 98.5% 0.2% 0.2% 0.2% 0.0% Propane 0.0% 0.0% 0.0% 0.0% 0.0% 0.0%0.0% 0.0% 1-Butene 0.0% 0.0% 2.7% 0.3% 3.2% 3.4% 3.4% 0.1% Isobutene0.0% 0.0% 4.5% 0.6% 5.3% 5.7% 5.7% 0.2% cis-2-butene 0.0% 0.0% 5.2% 0.0%6.2% 5.9% 5.9% 10.4% trans-2-butene 0.0% 0.0% 5.8% 0.0% 7.0% 7.1% 7.1%4.7% n-Butane 0.0% 0.0% 63.6% 0.3% 76.0% 77.6% 77.6% 54.7% 1-Pentene0.0% 0.0% 0.1% 0.0% 0.1% 0.0% 0.0% 1.2% cis-2-Pentene 0.0% 0.0% 0.2%0.0% 0.3% 0.0% 0.0% 3.6% trans-2-Pentene 0.0% 0.0% 0.4% 0.0% 0.5% 0.0%0.0% 7.0% 2-Methy-2- 0.0% 0.0% 0.5% 0.0% 0.5% 0.0% 0.0% 7.7% butene3-Methy-1- 0.0% 0.0% 0.1% 0.0% 0.1% 0.0% 0.0% 0.8% butene 2-Methy-1-0.0% 0.0% 0.3% 0.0% 0.3% 0.0% 0.0% 4.0% butene Sum of hexenes, 0.0% 0.0%0.3% 0.0% 0.5% 0.0% 0.0% 5.9% hexanes, and heavier Total mol % 100.0%100.0% 100.0% 100.0% 100.0% 100.0% 100.0% 100.0%

Example 2

The systems of FIG. 2 was also computer modeled using Aspen Plus®. Thesubsequent tables (Tables 9-16) depict the stream compositions andflowrates, as well as thermal properties for selected streams. Thesystem inlet stream composition and catalyst reaction rates used for themodel were the same as those of Example 1. The system inlet stream of 35wt. % cis-2-butene, 35 wt. % trans-2-butene, and 30 wt. % n-butane wasused for the model. The stream numbers corresponds with the stream orstream segment shown in FIG. 2. Simulations were run for 100% efficiencyand 80% efficiency. Additionally, data is provided on a weight basis anda mole basis for each simulation. Table 5 depicts data for a simulationof the system of FIG. 2 with 100% efficiency and shows components on amass basis. Table 6 depicts data for a simulation of the system of FIG.2 with 100% efficiency and shows components on a mole basis. Table 7depicts data for a simulation of the system of FIG. 2 with 80%efficiency and shows components on a mass basis. Table 8 depicts datafor a simulation of the system of FIG. 2 with 80% efficiency and showscomponents on a mole basis. Additionally, FIG. 4 depicts a bar graphdisplaying the product distribution of the system of FIG. 2 as shown inTable 5 where, on the bar graph, “Propylene” corresponds with the streamof transfer line 307, “Light Purge” corresponds with the stream oftransfer line 336, “C4 Purge” corresponds with the stream of transferline 316, and “C5+Heavy” corresponds with the stream of transfer line314.

TABLE 5 FIG. 2 with 100% efficiency in wt. % Stream Number 301A/B/C/D301E 332 301F 338 340 303A/B Mole Flow, 100.0 85.0 102.2 15.0 225.8225.8 328.0 kmol/hr Mass Flow, 5670 4819 4819 850 11831 11831 16650kg/hr Volumn Flow 6750 5737 6901 1012 3966 15244 26.9 m³/hr Enthalpy, MW0.6 0.5 0.9 0.1 −2.7 0.8 −4.5 MW, g/mol 56.7 56.7 47.2 56.7 52.4 52.450.8 Density, kg/m³ 0.84 0.84 0.70 0.84 2.98 0.78 619.0 COMPONENTS, wt %Ethylene 0.0% 0.0% 10.8% 0.0% 8.7% 5.3% 6.9% Propylene 0.0% 0.0% 30.9%0.0% 0.3% 11.1% 16.8% Propane 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0%1-Butene 0.0% 0.0% 4.4% 0.0% 3.2% 1.8% 2.6% Isobutene 0.0% 0.0% 9.3%0.0% 28.0% 28.0% 22.5% cis-2-butene 35.0% 35.0% 4.4% 35.0% 5.0% 1.8%2.5% trans-2-butene 35.0% 35.0% 5.3% 35.0% 5.8% 2.2% 3.1% n-Butane 30.0%30.0% 30.0% 30.0% 48.9% 48.9% 43.5% 1-Pentene 0.0% 0.0% 0.2% 0.0% 0.0%0.0% 0.1% cis-2-Pentene 0.0% 0.0% 0.3% 0.0% 0.0% 0.3% 0.3%trans-2-Pentene 0.0% 0.0% 0.6% 0.0% 0.0% 0.6% 0.6% 2-Methy-2- 0.0% 0.0%1.5% 0.0% 0.0% 0.0% 0.4% butene 3-Methy-1- 0.0% 0.0% 0.2% 0.0% 0.0% 0.0%0.1% butene 2-Methy-1- 0.0% 0.0% 0.8% 0.0% 0.0% 0.0% 0.3% butene Sum ofhexenes, 0.0% 0.0% 1.1% 0.0% 0.0% 0.0% 0.3% hexanes, and heavier Totalmol % 100.0% 100.0% 100.0% 100.0% 100.0% 100.0% 100.0% Stream Number 336334 306 307 308 316 312A/B 314 Mole Flow, 4.1 37.0 286.9 65.9 221.1 19.3173.8 27.9 kmol/hr Mass Flow, 116 1040 15494 2771 12723 1104 9940 1679kg/hr Volumn Flow 0.3 2.4 33.8 5.8 27.5 2.2 20.0 3.4 m³/hr Enthalpy, MW0.0 0.3 −3.8 0.1 −3.9 −0.3 −3.1 −0.6 MW, g/mol 28.1 28.1 54.0 42.1 57.657.2 57.2 60.1 Density, kg/m³ 438.1 438.1 458.0 477.4 462.2 497.0 497.0494.5 COMPONENTS, wt % Ethylene 99.0% 99.0% 0.0% 0.2% 0.0% 0.0% 0.0%0.0% Propylene 1.0% 1.0% 18.0% 99.5% 0.2% 0.3% 0.3% 0.0% Propane 0.0%0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 1-Butene 0.0% 0.0% 2.7% 0.0% 3.3%3.8% 3.8% 0.6% Isobutene 0.0% 0.0% 24.2% 0.3% 29.5% 33.3% 33.3% 4.3%cis-2-butene 0.0% 0.0% 2.7% 0.0% 3.3% 3.0% 3.0% 5.8% trans-2-butene 0.0%0.0% 3.3% 0.0% 4.0% 4.0% 4.0% 4.5% n-Butane 0.0% 0.0% 46.7% 0.0% 56.9%55.7% 55.7% 64.7% 1-Pentene 0.0% 0.0% 0.1% 0.0% 0.1% 0.0% 0.0% 0.7%cis-2-Pentene 0.0% 0.0% 0.3% 0.0% 0.4% 0.0% 0.0% 3.0% trans-2-Pentene0.0% 0.0% 0.7% 0.0% 0.8% 0.0% 0.0% 5.9% 2-Methy-2- 0.0% 0.0% 0.5% 0.0%0.6% 0.0% 0.0% 4.3% butene 3-Methy-1- 0.0% 0.0% 0.1% 0.0% 0.1% 0.0% 0.0%0.5% butene 2-Methy-1- 0.0% 0.0% 0.3% 0.0% 0.3% 0.0% 0.0% 2.4% buteneSum of hexenes, 0.0% 0.0% 0.3% 0.0% 0.5% 0.0% 0.0% 3.4% hexanes, andheavier Total mol % 100.0% 100.0% 100.0% 100.0% 100.0% 100.0% 100.0%100.0%

TABLE 6 FIG. 2 with 100% efficiency in mol % Stream Number 301A 301E 332301F 338 340 303A/B Mole Flow, 100.0 85.0 102.2 15.0 225.8 225.8 328.0kmol/hr Mass Flow, 5670 4819 4819 850 11831 11831 16650 kg/hr VolumnFlow 6750 5737 6901 1012 3966 15244 26.9 m³/hr Enthalpy, MW 0.6 0.5 0.90.1 −2.7 0.8 −4.5 MW, g/mol 56.7 56.7 47.2 56.7 52.4 52.4 50.8 Density,kg/m³ 0.84 0.84 0.70 0.84 2.98 0.78 619.0 COMPONENTS, mol % Ethylene0.0% 0.0% 18.2% 0.0% 16.3% 9.9% 12.5% Propylene 0.0% 0.0% 34.6% 0.0%0.4% 13.8% 20.3% Propane 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 1-Butene0.0% 0.0% 3.7% 0.0% 2.9% 1.7% 2.3% Isobutene 0.0% 0.0% 7.8% 0.0% 26.1%26.1% 20.4% cis-2-butene 35.4% 35.4% 3.7% 35.4% 4.7% 1.7% 2.3%trans-2-butene 35.4% 35.4% 4.5% 35.4% 5.5% 2.0% 2.8% n-Butane 29.3%29.3% 24.3% 29.3% 44.1% 44.1% 37.9% 1-Pentene 0.0% 0.0% 0.2% 0.0% 0.0%0.0% 0.1% cis-2-Pentene 0.0% 0.0% 0.2% 0.0% 0.0% 0.2% 0.2%trans-2-Pentene 0.0% 0.0% 0.4% 0.0% 0.0% 0.5% 0.4% 2-Methyl-2- 0.0% 0.0%1.0% 0.0% 0.0% 0.0% 0.3% butene 3-Methyl-1- 0.0% 0.0% 0.1% 0.0% 0.0%0.0% 0.1% butene 2-Methyl-1- 0.0% 0.0% 0.6% 0.0% 0.0% 0.0% 0.2% buteneSum of hexenes, 0.0% 0.0% 0.6% 0.0% 0.0% 0.0% 0.0% hexanes, and heavierTotal mol % 100.0% 100.0% 100.0% 100.0% 100.0% 100.0% 100.0% StreamNumber 336 334 306 307 308 316 312A/B 314 Mole Flow, 4.1 37.0 286.9 65.9221.1 19.3 173.8 27.9 kmol/hr Mass Flow, 116 1040 15494 2771 12723 11049940 1679 kg/hr Volumn Flow 0.3 2.4 33.8 5.8 27.5 2.2 20.0 3.4 m³/hrEnthalpy, MW 0.0 0.3 −3.8 0.1 −3.9 −0.3 −3.1 −0.6 MW, g/mol 28.1 28.154.0 42.1 57.6 57.2 57.2 60.1 Density, kg/m³ 438.1 438.1 458.0 477.4462.2 497.0 497.0 494.5 COMPONENTS, mol % Ethylene 99.3% 99.3% 0.1% 0.3%0.0% 0.0% 0.0% 0.0% Propylene 0.7% 0.7% 23.1% 99.5% 0.3% 0.3% 0.3% 0.0%Propane 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 1-Butene 0.0% 0.0% 2.6%0.0% 3.4% 3.8% 3.8% 0.6% Isobutene 0.0% 0.0% 23.3% 0.2% 30.2% 33.9%33.9% 4.6% cis-2-butene 0.0% 0.0% 2.6% 0.0% 3.4% 3.0% 3.0% 6.2%trans-2-butene 0.0% 0.0% 3.2% 0.0% 4.1% 4.0% 4.0% 4.8% n-Butane 0.0%0.0% 43.4% 0.0% 56.3% 54.8% 54.8% 66.9% 1-Pentene 0.0% 0.0% 0.1% 0.0%0.1% 0.0% 0.0% 0.6% cis-2-Pentene 0.0% 0.0% 0.3% 0.0% 0.3% 0.0% 0.0%2.6% trans-2-Pentene 0.0% 0.0% 0.5% 0.0% 0.7% 0.0% 0.0% 5.0% 2-Methyl-2-0.0% 0.0% 0.4% 0.0% 0.5% 0.0% 0.0% 3.7% butene 3-Methyl-1- 0.0% 0.0%0.1% 0.0% 0.1% 0.0% 0.0% 0.5% butene 2-Methyl-1- 0.0% 0.0% 0.2% 0.0%0.3% 0.0% 0.0% 2.0% butene Sum of hexenes, 0.0% 0.0% 0.0% 0.0% 0.3% 0.0%0.0% 2.4% hexanes, and heavier Total mol % 100.0% 100.0% 100.0% 100.0%100.0% 100.0% 100.0% 100.0%

TABLE 7 FIG. 2 with 80% efficiency in wt. % Stream Number 301A 301E 332301F 338 340 303A/B Mole Flow, 100.0 85.0 98.8 15.0 275.6 275.6 374.4kmol/hr Mass Flow, 5670 4819 4819 850 14943 14943 19762 kg/hr VolumnFlow 6750 5737 6668 1012 4605 16513 31.5 m³/hr Enthalpy, MW 0.6 0.5 0.90.1 −4.0 −0.3 −6.0 MW, g/mol 56.7 56.7 48.8 56.7 54.2 54.2 52.8 Density,kg/m³ 0.84 0.84 0.72 0.84 3.24 0.90 627.5 COMPONENTS, wt % Ethylene 0.0%0.0% 8.7% 0.0% 5.3% 3.2% 4.5% Propylene 0.0% 0.0% 24.7% 0.0% 0.2% 8.2%12.3% Propane 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 1-Butene 0.0% 0.0% 3.5%0.0% 4.0% 3.3% 3.4% Isobutene 0.0% 0.0% 7.4% 0.0% 22.4% 19.9% 16.8%cis-2-butene 35.0% 35.0% 10.5% 35.0% 7.5% 4.0% 5.6% trans-2-butene 35.0%35.0% 11.3% 35.0% 9.0% 4.8% 6.4% n-Butane 30.0% 30.0% 30.0% 30.0% 54.0%54.0% 48.1% 1-Pentene 0.0% 0.0% 0.2% 0.0% 0.0% 0.0% 0.1% cis-2-Pentene0.0% 0.0% 0.3% 0.0% 0.0% 0.8% 0.7% trans-2-Pentene 0.0% 0.0% 0.5% 0.0%0.1% 1.6% 1.3% 2-Methy-2- 0.0% 0.0% 1.2% 0.0% 0.0% 0.0% 0.3% butene3-Methy-1- 0.0% 0.0% 0.2% 0.0% 0.0% 0.0% 0.1% butene 2-Methy-1- 0.0%0.0% 0.7% 0.0% 0.0% 0.0% 0.2% butene Sum of hexenes, 0.0% 0.0% 1.0% 0.0%0.0% 0.1% 0.1% hexanes, and heavier Total mol % 100.0% 100.0% 100.0%100.0% 100.0% 100.0% 100.0% Stream Number 336 334 306 307 308 316 312A/B314 Mole Flow, 3.2 28.6 342.6 57.1 285.5 25.8 232.1 27.7 kmol/hr MassFlow, 89 805 18868 2402 16466 1476 13288 1702 kg/hr Volumn Flow 0.2 1.841.4 5.0 35.6 3.0 26.8 3.4 m³/hr Enthalpy, MW 0.0 0.2 −5.0 0.1 −5.1 −0.5−4.3 −0.5 MW, g/mol 28.1 28.1 55.1 42.1 57.7 57.3 57.3 61.4 Density,kg/m³ 438.1 438.1 455.3 477.4 462.5 496.7 496.7 500.3 COMPONENTS, wt %Ethylene 99.0% 99.0% 0.0% 0.2% 0.0% 0.0% 0.0% 0.0% Propylene 1.0% 1.0%12.8% 99.5% 0.1% 0.2% 0.2% 0.0% Propane 0.0% 0.0% 0.0% 0.0% 0.0% 0.0%0.0% 0.0% 1-Butene 0.0% 0.0% 3.5% 0.0% 4.0% 4.5% 4.5% 0.3% Isobutene0.0% 0.0% 17.6% 0.3% 20.2% 22.4% 22.4% 1.3% cis-2-butene 0.0% 0.0% 5.9%0.0% 6.7% 6.2% 6.2% 10.8% trans-2-butene 0.0% 0.0% 6.7% 0.0% 7.7% 7.8%7.8% 6.3% n-Butane 0.0% 0.0% 50.4% 0.0% 57.7% 58.8% 58.8% 49.0%1-Pentene 0.0% 0.0% 0.1% 0.0% 0.1% 0.0% 0.0% 0.5% cis-2-Pentene 0.0%0.0% 0.7% 0.0% 0.8% 0.0% 0.0% 7.6% trans-2-Pentene 0.0% 0.0% 1.4% 0.0%1.6% 0.1% 0.1% 15.0% 2-Methy-2- 0.0% 0.0% 0.3% 0.0% 0.4% 0.0% 0.0% 3.4%butene 3-Methy-1- 0.0% 0.0% 0.1% 0.0% 0.1% 0.0% 0.0% 0.4% butene2-Methy-1- 0.0% 0.0% 0.2% 0.0% 0.2% 0.0% 0.0% 1.9% butene Sum ofhexenes, 0.0% 0.0% 0.1% 0.0% 0.2% 0.0% 0.0% 3.4% hexanes, and heavierTotal mol % 100.0% 100.0% 100.0% 100.0% 100.0% 100.0% 100.0% 100.0%

TABLE 8 FIG. 2 with 80% efficiency in mol % Stream Number 301A 301E 332301F 338 340 303A/B Mole Flow, 100.0 85.0 98.8 15.0 275.6 275.6 374.4kmol/hr Mass Flow, 5670 4819 4819 850 14943 14943 19762 kg/hr VolumnFlow 6750 5737 6668 1012 4605 16513 31.5 m³/hr Enthalpy, MW 0.6 0.5 0.90.1 −4.0 −0.3 −6.0 MW, g/mol 56.7 56.7 48.8 56.7 54.2 54.2 52.8 Density,kg/m³ 0.84 0.84 0.72 0.84 3.24 0.90 627.5 COMPONENTS, mol % Ethylene0.0% 0.0% 15.1% 0.0% 10.3% 6.1% 8.5% Propylene 0.0% 0.0% 28.7% 0.0% 0.3%10.6% 15.4% Propane 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 1-Butene 0.0%0.0% 3.1% 0.0% 3.8% 3.2% 3.2% Isobutene 0.0% 0.0% 6.5% 0.0% 22.8% 19.2%15.8% cis-2-butene 35.4% 35.4% 9.2% 35.4% 7.3% 3.9% 5.3% trans-2-butene35.4% 35.4% 9.8% 35.4% 8.7% 4.7% 6.0% n-Butane 29.3% 29.3% 25.2% 29.3%50.3% 50.3% 43.7% 1-Pentene 0.0% 0.0% 0.1% 0.0% 0.0% 0.0% 0.0%cis-2-Pentene 0.0% 0.0% 0.2% 0.0% 0.0% 0.6% 0.5% trans-2-Pentene 0.0%0.0% 0.3% 0.0% 0.1% 1.3% 1.0% 2-Methyl-2- 0.0% 0.0% 0.8% 0.0% 0.0% 0.0%0.2% butene 3-Methyl-1- 0.0% 0.0% 0.1% 0.0% 0.0% 0.0% 0.0% butene2-Methyl-1- 0.0% 0.0% 0.5% 0.0% 0.0% 0.0% 0.1% butene Sum of hexenes,0.0% 0.0% 0.5% 0.0% 0.0% 0.1% 0.1% hexanes, and heavier Total mol %100.0% 100.0% 100.0% 100.0% 100.0% 100.0% 100.0% Stream Number 336 334306 307 308 316 312A/B 314 Mole Flow, 3.2 28.6 342.6 57.1 285.5 25.8232.1 27.7 kmol/hr Mass Flow, 89 805 18868 2402 16466 1476 13288 1702kg/hr Volumn Flow 0.2 1.8 41.4 5.0 35.6 3.0 26.8 3.4 m³/hr Enthalpy, MW0.0 0.2 −5.0 0.1 −5.1 −0.5 −4.3 −0.5 MW, g/mol 28.1 28.1 55.1 42.1 57.757.3 57.3 61.4 Density, kg/m³ 438.1 438.1 455.3 477.4 462.5 496.7 496.7500.3 COMPONENTS, mol % Ethylene 99.3% 99.3% 0.0% 0.3% 0.0% 0.0% 0.0%0.0% Propylene 0.7% 0.7% 16.7% 99.5% 0.2% 0.2% 0.2% 0.0% Propane 0.0%0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 1-Butene 0.0% 0.0% 3.5% 0.0% 4.1%4.6% 4.6% 0.4% Isobutene 0.0% 0.0% 17.3% 0.2% 20.7% 22.8% 22.8% 1.4%cis-2-butene 0.0% 0.0% 5.8% 0.0% 6.9% 6.4% 6.4% 11.8% trans-2-butene0.0% 0.0% 6.6% 0.0% 7.9% 8.0% 8.0% 6.9% n-Butane 0.0% 0.0% 47.7% 0.0%57.3% 57.9% 57.9% 51.7% 1-Pentene 0.0% 0.0% 0.0% 0.0% 0.1% 0.0% 0.0%0.5% cis-2-Pentene 0.0% 0.0% 0.6% 0.0% 0.7% 0.0% 0.0% 6.7%trans-2-Pentene 0.0% 0.0% 1.1% 0.0% 1.3% 0.1% 0.1% 13.1% 2-Methyl-2-0.0% 0.0% 0.2% 0.0% 0.3% 0.0% 0.0% 3.0% butene 3-Methyl-1- 0.0% 0.0%0.0% 0.0% 0.1% 0.0% 0.0% 0.4% butene 2-Methyl-1- 0.0% 0.0% 0.1% 0.0%0.2% 0.0% 0.0% 1.6% butene Sum of hexenes, 0.0% 0.0% 0.1% 0.0% 0.1% 0.0%0.0% 2.4% hexanes, and heavier Total mol % 100.0% 100.0% 100.0% 100.0%100.0% 100.0% 100.0% 100.0%

Table 17 shows butene conversion, propylene selectivity, and propyleneyield for the embodiments of FIGS. 1 and 2. The data was determinedusing Aspen Plus® with the conditions as those provided for Tables 1 and9.

The butene conversion is defined as:

$\left( {1 - \frac{{Mass}\mspace{14mu}{flow}\mspace{14mu}{of}\mspace{14mu} 2{\_ butene}\mspace{14mu}{in}\mspace{14mu}{combined}\mspace{14mu}{reactor}\mspace{14mu}{effluent}}{{Mass}\mspace{14mu}{flow}\mspace{14mu}{of}\mspace{14mu} 2{\_ butene}\mspace{14mu}{in}\mspace{14mu}{combined}\mspace{14mu}{reactor}\mspace{14mu}{feed}}} \right)*100\%$

The propylene selectivity is defined as:

$\left( \frac{\begin{matrix}{{{Mass}\mspace{14mu}{flow}\mspace{14mu}{of}\mspace{14mu}{propylene}\mspace{14mu}{in}\mspace{14mu}{reactor}\mspace{14mu}{effluent}} -} \\{{Mass}\mspace{14mu}{flow}\mspace{14mu}{of}\mspace{14mu}{propylene}\mspace{14mu}{in}\mspace{14mu}{reactor}\mspace{14mu}{feed}}\end{matrix}}{\begin{matrix}{{Mass}\mspace{14mu}{flow}\mspace{14mu}{of}\mspace{14mu} 2{\_ butene}\mspace{14mu}{in}\mspace{14mu}{reactor}\mspace{14mu}{feed}*} \\{{butene}\mspace{14mu}{conversion}\mspace{14mu}{rate}}\end{matrix}} \right)*100\%$

The propylene yield is defined as:

$\left( \frac{{Total}\mspace{14mu}{Propylene}\mspace{14mu}{Produced}\mspace{11mu}\left( {{wt}.\mspace{14mu}\%} \right)}{{Total}\mspace{14mu} 2{\_ butene}\mspace{14mu}{in}\mspace{14mu}{Feed}\mspace{11mu}\left( {{wt}.\mspace{14mu}\%} \right)} \right)*100\%$

TABLE 17 Embodiment Embodiment of of FIG. 1 FIG. 2 Butene Conversion80.6% 79.9% Propylene selectivity 60.5% 74.2% Propylene yield 79.8%69.6%

For the purposes of describing and defining the present disclosure it isnoted that the term “about” are utilized in this disclosure to representthe inherent degree of uncertainty that may be attributed to anyquantitative comparison, value, measurement, or other representation.The term “about” are also utilized in this disclosure to represent thedegree by which a quantitative representation may vary from a statedreference without resulting in a change in the basic function of thesubject matter at issue. Additionally, the term “consisting essentiallyof” is used in this disclosure to refer to quantitative values that donot materially affect the basic and novel characteristic(s) of thedisclosure. For example, a chemical stream “consisting essentially” of aparticular chemical constituent or group of chemical constituents shouldbe understood to mean that the stream includes at least about 99.5% of athat particular chemical constituent or group of chemical constituents.

It is noted that one or more of the following claims utilize the term“where” as a transitional phrase. For the purposes of defining thepresent technology, it is noted that this term is introduced in theclaims as an open-ended transitional phrase that is used to introduce arecitation of a series of characteristics of the structure and should beinterpreted in like manner as the more commonly used open-ended preambleterm “comprising.”

It should be understood that any two quantitative values assigned to aproperty may constitute a range of that property, and all combinationsof ranges formed from all stated quantitative values of a given propertyare contemplated in this disclosure. It should be appreciated thatcompositional ranges of a chemical constituent in a stream or in areactor should be appreciated as containing, in some embodiments, amixture of isomers of that constituent. For example, a compositionalrange specifying butene may include a mixture of various isomers ofbutene. It should be appreciated that the examples supply compositionalranges for various streams, and that the total amount of isomers of aparticular chemical composition can constitute a range.

Having described the subject matter of the present disclosure in detailand by reference to specific embodiments, it is noted that the variousdetails described in this disclosure should not be taken to imply thatthese details relate to elements that are essential components of thevarious embodiments described in this disclosure, even in cases where aparticular element is illustrated in each of the drawings that accompanythe present description. Rather, the claims appended hereto should betaken as the sole representation of the breadth of the presentdisclosure and the corresponding scope of the various embodimentsdescribed in this disclosure. Further, it will be apparent thatmodifications and variations are possible without departing from thescope of the appended claims.

What is claimed is:
 1. A process for producing propylene, the processcomprising: at least partially metathesizing a first portion of a firststream to form a first metathesis-reaction product, the first streamcomprising butene; at least partially cracking the firstmetathesis-reaction product to form a cracking-reaction productcomprising propylene; combining a second stream with a second portion ofthe first stream to a form a mixed stream, the second stream comprisingethylene; and at least partially metathesizing the mixed stream to forma second metathesis-reaction product comprising propylene.
 2. Theprocess of claim 1, where the cracking reaction product furthercomprises ethylene.
 3. The process of claim 1, further comprisingdividing the first stream into the first portion and the second portion.4. The process of claim 1, where the first stream comprises at least 10wt. % butene.
 5. The process of claim 1, further comprising combiningthe cracking-reaction product with the second metathesis-reactionproduct to form a combined stream.
 6. The process of claim 5, furthercomprising at least partially separating ethylene from the combinedstream.
 7. The process of claim 5, where the combined stream comprisesat least 10 wt. % propylene.
 8. The process of claim 1, where thecracking utilizes a mordenite framework inverted (MFI) structured silicacatalyst.
 9. The process of claim 1, where the metathesis utilizes amesoporous silica catalyst impregnated with metal oxide.
 10. A processfor producing propylene, the process comprising: dividing a first streaminto a first portion and a second portion, the first stream comprisingbutene; at least partially metathesizing a first portion of a firststream to form a first metathesis-reaction product; at least partiallycracking the first metathesis-reaction product to form acracking-reaction product comprising propylene; and at least partiallymetathesizing the second portion of the first stream to form a secondmetathesis-reaction product comprising propylene.
 11. The process ofclaim 10, where the cracking reaction product further comprisesethylene.
 12. The process of claim 10, where the first stream comprisesat least 10 wt. % butene.
 13. The process of claim 10, furthercomprising combining the cracking-reaction product with the secondmetathesis-reaction product to form a combined stream.
 14. The processof claim 13, further comprising at least partially separating ethylenefrom the combined stream.
 15. The process of claim 13, where thecombined stream comprises at least 10 wt. % propylene.
 16. The processof claim 10, further comprising combining the second portion of thefirst stream with a stream comprising ethylene prior to the metathesisof the second portion of the first stream.
 17. The process of claim 10,wherein the cracking utilizes a mordenite framework inverted (MFI)structured silica catalyst.
 18. The process of claim 10, wherein themetathesis utilizes a mesoporous silica catalyst impregnated with metaloxide.